There exists a global demand for low- or reduced-fat products. Donuts are consumed worldwide on a large scale. But fried donuts contain quite a lot of fat due to the frying process.
Therefore there is an interest in having donuts with lower amounts of fat.
Donuts generally fall into two broad categories: cake donuts, leavened by a baking powder chemical reaction which produces carbon dioxide; and yeast-raised donuts, leavened by yeast enzymes which react with sugar during fermentation to produce carbon dioxide and ethyl alcohol.
Conventional cake donuts are prepared from a batter which is deposited into hot oil for frying. Yeast-raised donuts are produced from a dough which is permitted to ferment before being fried in oil.
Both yeast raised and cake donuts contain approximately 25-30% fat of which 80-85% is absorbed frying fat.
While donuts are typically fried, they may also be baked. Several patent applications relate to baked donuts with possibly a reduced fat content compared to fried donuts.
U.S. Pat. No. 5,804,243 e.g. discloses a cake donut made with 20-30% of a thermally reversible gel. The reversible gel comprises insoluble water-binding fiber and thermally-reversible hydrocolloid agent. The donuts are baked in an oven at a temperature between 190 and 220° C.
Patent application US2006/0182865 discloses a process to obtain low fat donuts. In this process the donuts are baked in a convection oven at a temperature between 180 and 195° C.
A finished fried donut has a very characteristic short bite and soft texture, which is difficult to obtain through baking. Baking e.g. often results in a more dry bread-like substance.
EP 1 263 291 discloses a method for the production of baked yeast-raised donuts with the taste and texture of a fried yeast-raised donut, the method comprising two spraying steps to coat the donut with cooking fat, and an intervening baking step.
Thus far there appear to have been no proposals for preparing donuts other than by frying or baking.
Steamed baking applications are very popular in China, Japan and the rest of Asia (South-East Asia), yet steaming applications appear to have been limited thus far to steamed buns, breads and the like (see e.g. JP10150918 and patent application US2002/0031575).